Fluoroelastomer surfaces and methods thereof

ABSTRACT

Fluoroelastomer surfaces and a method for providing a fluoroelastomer surface on a supporting substrate which includes dissolving a solid fluoroelastomer in a solvent, adding an amino silane in order to effect coupling and crosslinking and to form a resulting homogeneous fluoroelastomer solution, and subsequently providing a layer of the homogeneous fluoroelastomer solution to the supporting substrate is provided herein.

CROSS REFERENCE TO RELATED APPLICATIONS

Attention is directed to the following copending applications assigned to the assignee of the present application. Attorney Docket number D194320 U.S. application Ser. No. 08/625,568 filed Mar. 28, 1996, entitled, "Volume Grafted Elastomer Surfaces and Methods Thereof," Attorney Docket No. 0/94318 U.S. application Ser. No. 08/623,290 filed Mar. 28, 1996, entitled, "Fluoroelastomer Surfaces and Methods Thereof,". Attorney Docker No. D/94356 U.S. application Ser. No. 08/625,566 filed Mar. 28, 1996, entitled, "Fluoroelastomer Members." and Attorney Docket No. D/94356Q application Ser. No. 08/623,273, filed Mar. 28, 1996, entitled, "Fluoroelastomer Members." The disclosures of these applications are hereby incorporated by reference in their entirety.

BACKGROUND OF THE INVENTION

The present invention relates to elastomer surfaces and a process for providing an elastomer surface, and more specifically a fluoroelastomer, hydrofluoroelastomer or VITON® hydrofluoroelastomer surface, on a supporting substrate. The resulting surfaces are useful as surfaces for components in electrostatographic processes, especially xerographic processes, including the surfaces of donor rolls, pressure rolls, fuser rolls, toner transfer belts or roller surfaces and the like. In embodiments, the present invention allows for a decrease in unit manufacturing costs by dispensing with the need for additional coupling and crosslinking agents during the curing process in the overall process for providing a fluoroelastomer surface. Further, with the present process, a roll milling step and the final ball milling step are not necessary, resulting in decreased time required for curing and further, resulting in a decrease in cost. The resulting fluoroelastomer surface has sufficient toughness and increased chemical, physical and thermal stability when compared to surfaces cured using known methods.

In a typical electrostatographic reproducing apparatus, a light image of an original to be copied is recorded in the form of an electrostatic latent image upon a photosensitive member and the latent image is subsequently rendered visible by the application of electroscopic thermoplastic resin particles which are commonly referred to as toner. The visible toner image is then in a loose powdered form and can be easily disturbed or destroyed. The toner image is usually fixed or fused upon a support which may be the photosensitive member itself or other support sheet such as plain paper.

The use of thermal energy for fixing toner images onto a support member is well known. To fuse electroscopic toner material onto a support surface permanently by heat, it is usually necessary to elevate the temperature of the toner material to a point at which the constituents of the toner material coalesce and become tacky. This heating causes the toner to flow to some extent into the fibers or pores of the support member. Thereafter, as the toner material cools, solidification of the toner material causes the toner material to be firmly bonded to the support.

Typically, the thermoplastic resin particles are fused to the substrate by heating to a temperature of between about 90° C. to about 200° C. or higher depending upon the softening range of the particular resin used in the toner. It is undesirable, however, to increase the temperature of the substrate substantially higher than about 250° C. because of the tendency of the substrate to discolor or convert into a fire, at such elevated temperatures, particularly when the substrate is paper.

Several approaches to thermal fusing of electroscopic toner images have been described. These methods include providing the application of heat and pressure substantially concurrently by various means, a roll pair maintained in pressure contact, a belt member in pressure contact with a roll, and the like. Heat may be applied by heating one or both of the rolls, plate members or belt members. The fusing of the toner particles takes place when the proper combination of heat, pressure and contact time are provided. The balancing of these parameters to bring about the fusing of the toner particles is well known in the art, and can be adjusted to suit particular machines or process conditions.

During operation of a fusing system in which heat is applied to cause thermal fusing of the toner particles onto a support, both the toner image and the support are passed through a nip formed between the roll pair, or plate or belt members. The concurrent transfer of heat and the application of pressure in the nip affects the fusing of the toner image onto the support. It is important in the fusing process that no offset of the toner particles from the support to the fuser member take place during normal operations. Toner particles offset onto the fuser member may subsequently transfer to other parts of the machine or onto the support in subsequent copying cycles, thus increasing the background or interfering with the material being copied there. The referred to "hot offset" occurs when the temperature of the toner is increased to a point where the toner particles liquefy and a splitting of the molten toner takes place during the fusing operation with a portion remaining on the fuser member. The hot offset temperature or degradation of the hot offset temperature is a measure of the release property of the fuser roll, and accordingly it is desired to provide a fusing surface which has a low surface energy to provide the necessary release. To ensure and maintain good release properties of the fuser roll, it has become customary to apply release agents to the fuser roll during the fusing operation. Typically, these materials are applied as thin films of, for example, silicone oils to prevent toner offset.

Particularly preferred fusing systems are comprised of a heated cylindrical fuser roll having a fusing surface which is backed by a cylindrical pressure roll forming a fusing nip therebetween. A release agent donor roll is also provided to deliver release agent to the fuser roll. While the physical and performance characteristics of each of these rolls, and particularly of their functional surfaces are not precisely the same depending on the various characteristics of the fusing system desired, the same classes of materials are typically used for one or more of the rolls in a fusing system in an electrostatographic printing system.

Fusing systems using fluoroelastomers as fuser members are described in U.S. Pat. No. 4,264,181 to Lentz et al., U.S. Pat. No. 4,257,699 to Lentz, and U.S. Pat. No. 4,272,179 to Seanor, all commonly assigned to the assignee of the present invention. The disclosures of these patents are hereby incorporated within in their entirety.

U.S. Pat. No. 5,017,432, the disclosure of which is hereby incorporated by reference, describes a fusing surface layer made from a specific fluoroelastomer, poly(vinylidenefluoride-hexafluoropropylene-tetrafluoroethylene) where the vinylidenefluoride is present in an amount less than 40 weight percent. The patent further discloses curing the fluoroelastomer with VITON® Curative No. 50 (VC-50) available from E.I. Du Pont de Nemours, Inc. which is soluble in a solvent solution of the polymer at low base levels and is readily available at the reactive sites for crosslinking. The patent also discloses use of a metal oxide (such as cupric oxide) in addition to VC-50 for curing.

U.S. Pat. No. 5,061,965 to Ferguson et al., the disclosure of which is hereby incorporated by reference in its entirety, discloses an elastomer release agent donor layer comprising poly(vinylidenefluoride-hexafluoropropylene-tetrafluoroethylene) and a metal oxide, where the vinylidenefluoride is present in an amount less than 40 weight percent. The release agent donor layer is cured with a curing agent in the presence of an inorganic base.

Generally, the process for providing the elastomer surface on the supporting substrate, e.g., donor roll, pressure roll, fuser roll, toner transfer belt or roller surfaces, etc., includes dissolving the fluoroelastomer in a typical solvent, followed by addition of a dehydrofluorination agent. The dehydrofluorinating agents create double bonds in the backbone which provide crosslinking cites on the fluoroelastomer. Next, a nucleophilic curing agent which incorporates an accelerator and a crosslinking agent is added, followed by addition of the basic metal oxides in particulate form which can act as acid acceptors. The solution is ball milled for extended period of time resulting in the formation of fine dispersion which is then used to fabricate the elastomer surfaces by conventional fabrication techniques. After the elastomer is provided on the substrate, the substrate is subjected to a step heat curing process.

The curing step can be considered an essential part of the preparation of fluoroelastomers surfaces. The level of cure is very important in that it affects the high temperature stability along with both chemical and physical properties of the elastomers. High temperature stability is crucial for fusing subsystem applications, whereas incomplete curing can adversely effect the transfer efficiencies of liquid and dry toners. The details of the curing mechanisms are described in A. L. Logothetis, "Chemistry Of Fluorocarbon Elastomers", in Progress in Polymer Science, Vol. 14: pages 251-296, (1989). There are three known categories of curing agents including diamines and their carbamate salts, peroxides and bisphenol based diols.

The preferred curing agents have been the basic metal oxides (MgO and Ca(OH)₂) and aliphatic and aromatic amines, where the aromatic groups may be benzene, toluene, naphthalene, anthracene, etc. In the diamine category, hexamethylenediamine is the most commonly used curing agent. The particularly preferred curing agents are the nucleophilic curing agents such as VC-50 which incorporates an accelerator (such as a quaternary phosphonium salt or salts) and a crosslinking agent (bisphenol AF). VC-50 is preferred due to the more thermally stable product it provides. Metal oxides like MgO can be used here as acid acceptors. However, the basic metal oxides can be used as either the dehydrofluorinating agent or as a curing agent.

Examples of peroxides include bis (2,4-dichlorobenzoyl) peroxide, di-benzoyl peroxide, di-cumyl peroxide, di-tertiary butyl peroxide, and 2,5-dimethyl-2,5-bis (t-butyl peroxy) hexane. Fluorocarbon free radical peroxide cures usually incorporate a cure site monomer, CSM, (e.g., bromotrifluoroethylene) as a reactivity site on the fluorocarbon polymer backbone and use a coagent such as triallyisocyanurate, TAIC, as the bridging crosslink to form the network. The three allyl groups in the TAMC are the bonding sites in the crosslinker and produce a three dimensional network. Heat (and possibly pressure) can be used to induce a peroxide (e.g. 2,5-bis -(t-butylperoxy)-2.5-dimethylhexane) to split into radicals. This, in turn, initiates radical formation at the CSM of polymer chains and in the allyl groups of the TAIC. The TAIC then combines with the polymer radical intermediates producing a crosslinked elastomer. Metal oxides such as MgO and Ca(OH)₂ can scavenge any hydrogen fluoride that could be generated.

Known curing processes such as those listed above require the addition of curing agents and crosslinking agents, in addition to dehydrofluorinating agents. These curing and crosslinking agents increase the cost of the curing process. In addition, when metal oxides are used, a roll milling and/or a ball milling step is normally required. The roll milling step lasts approximately 24 hours. Similarly, the ball milling step can be an extremely costly and time consuming procedure, requiring anywhere from 2 to 24 hours. In addition, the curing procedure must be followed very carefully and in specific detail in order to form fluoroelastomers with sufficient chemical, physical and thermal stability, along with sufficient toughness.

Therefore, a more cost effective and less time consuming method of providing a fluoroelastomer surface, which results in elastomers having sufficient toughness as well as sufficient chemical, physical and thermal stability is desired.

SUMMARY OF THE INVENTION

Examples of objects of the present invention include:

It is an object of the present invention to provide electrophotographic components and methods with many of the advantages indicated herein.

It is an object of the present invention to provide a fluoroelastomer surface together with a method for providing the fluoroelastomer surface on a supporting substrate which does not require the use of additional coupling and crosslinking agents, along with basic metal oxides.

It is another object of the present invention to provide a fluoroelastomer surface together with a method for providing the fluoroelastomer surface on a supporting substrate which does not require a time consuming and costly ball milling step or roll milling step.

Yet another object of the present invention is to provide a fluoroelastomer surface together with a method for providing the fluoroelastomer surface on a supporting substrate which does not require the use of a curative which requires redispersing.

It is further an object of the present invention to provide a fluoroelastomer surface which has sufficient chemical, physical and thermal stability, along with sufficient toughness.

Another object of the present invention is to provide a method for providing a fluoroelastomer surface on a supporting substrate which is more cost effective than known methods.

Many of the above objects have been met by the present invention, in embodiments, which includes: a method for providing a fluoroelastomer surface on a supporting substrate comprising the steps of: a) dissolving a fluoroelastomer in a solvent; b) adding an amino silane in an amount of from about 0.5 to about 10 weight percent based on the weight of fluoroelastomer in order to form a resulting homogeneous fluoroelastomer solution; and c) subsequently providing a layer of the homogeneous fluoroelastomer solution to said supporting substrate.

The fluoroelastomer surface provided by this method, the embodiments of which are further described herein, exhibits sufficient chemical, physical and thermal stability, along with sufficient toughness without the need for additional costly materials such as coupling and crosslinking agents, along with basic metal oxides, and without the time consuming and costly roll milling and/or ball milling step.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 represents a sectional view of a fuser system which may use the fuser member of the present invention.

DETAILED DESCRIPTION OF THE PRESENT INVENTION

A known fusing system is comprised of a heated cylindrical fuser roll having a fusing surface which is backed by a cylindrical pressure roll forming a fusing nip therebetween. A release agent donor roll is also provided to deliver release agent to the fuser roll. While the physical and performance characteristics of each of these rolls, and particularly of their functional surfaces are not precisely the same depending on the various characteristics of the fusing system desired, the same classes of materials are typically used for one or more of the rolls in a fusing system in an electrostatographic printing system.

The present process, in embodiments, enables surfaces as described in conjunction with a fuser assembly as shown in FIG. 1 where the numeral 1 designates a fuser roll comprising elastomer surface 2 upon a suitable base member 4, a hollow cylinder or core fabricated from any suitable metal, such as aluminum, anodized aluminum, steel, nickel, copper, and the like, having a suitable heating element 6 disposed in the hollow portion thereof which is coextensive with the cylinder. Backup or pressure roll 8 cooperates with fuser roll 1 to form a nip or contact arc 10 through which a copy paper or other substrate 12 passes such that toner images 14 thereon contact elastomer surface 2 of fuser roll 1. As shown in FIG. 1, the backup roll 8 has a rigid steel core 16 with an elastomer surface or layer 18 thereon. Sump 20 contains polymeric release agent 22 which may be a solid or liquid at room temperature, but it is a fluid at operating temperatures.

In the embodiment shown in FIG. 1 for applying the polymeric release agent 22 to elastomer surface 2, two release agent delivery rolls 17 and 19 rotatably mounted in the direction indicated are provided to transport release agent 22 to elastomer surface 2. Delivery roll 17 is partly immersed in the sump 20 and transports on its surface release agent from the sump to the delivery roll 19. By using a metering blade 24, a layer of polymeric release fluid can be applied initially to delivery roll 19 and subsequently to elastomer 2 in controlled thickness ranging from submicrometer thickness to thickness of several micrometers of release fluid. Thus, by metering device 24, about 0.1 to 2 micrometers or greater thicknesses of release fluid can be applied to the surface of elastomer 2.

Examples of the fluoroelastomers useful in the practice of the present invention are those described in detail in U.S. Pat. Nos. 5,166,031, 5,281,506, 5,366,772, 5,370,931, 4,257,699, 5,017,432 and 5,061,965, the disclosures of which are incorporated by reference herein in their entireties. As described therein these fluoroelastomers, particularly from the class of copolymers and terpolymers of vinylidenefluoride hexafluoropropylene and tetrafluoroethylene, are known commercially under various designations as VITON A®, VITON B®, VITON E®, VITON E60C®, VITON E430®, VITON 910®, VITON GH® and VITON GF®. The VITON® designation is a Trademark of E.I. Du Pont de Nemours, Inc. Other commercially available materials include FLUOREL 2170@, FLUOREL 21740, FLUOREL 2176®, FLUOREL 2177® and FLUOREL LVS 76® FLUOREL® being a Trademark of 3M Company. Additional commercially available materials include AFLAS™ a poly(propylene-tetrafluoroethylene) and FLUOREL II® (LII900) a poly(propylenetetrafluoroethylenevinylidenefluoride) both also available from 3M Company, as well as the Tecnoflons identified as FOR-60KIRW®, FOR-LHFOZ®, NM® FOR-THFO®, FOR-TFS®, TH® TN505® available from Montedison Specialty Chemical Company. Some VITON compositions contain small amounts of a bromine terminated olefin as a cure site monomer. This allows for curing with dinucleophiles or peroxides.

In a preferred embodiment, the fluoroelastomer is one having a relatively low quantity of vinylidenefluoride, such as in VITON GFO®, available from E.I. Du Pont de Nemours, Inc. The VITON GF® has 35 weight percent of vinylidenefluoride, 34 weight percent of hexafluoropropylene and 29 weight percent of tetrafluoroethylene with 2 weight percent cure site monomer. The amount of fluoroelastomer used to provide the surface of the present invention is dependent on the amount necessary to form the desired thickness of the layer or layers of surface material. Specifically, the fluoroelastomer is added in an amount of from about 1 to about 75 percent, preferably about 5 to about 30 percent by weight of total solids. Total solids as used herein refers to the total amount by weight of fluoroelastomer, solvent and any additives or adjuvants.

Any known solvent suitable for dissolving a fluoroelastomer may be used in the present invention. Examples of suitable solvents for the present invention include methyl ethyl ketone, methyl isobutyl ketone and the like. The solvent is used in an amount sufficient to dissolve the fluoroelastomer. Specifically, the solvent is added in an amount of from about 25 to about 99 weight percent, preferably from about 70 to about 95 weight percent of total solids. The fluoroelastomer is dissolved in the solvent by known means such as by stirring. It is preferred to stir the mixture vigorously by hand or by using a mechanical stirrer. The stirring should continue for from about 1 to about 10 hours, preferably from about 2 to about 5 hours.

Known dehydrofluorinating agents which attack the fluoroelastomer generating unsaturation are strong nucleophilic agents such as peroxides, hydrides, bases, oxides, etc. Examples of strong nucleophilic agents include primary, secondary and tertiary, aliphatic and aromatic amines, where the aliphatic and aromatic amines have from about 2 to about 15 carbon atoms. It also includes aliphatic and aromatic diamines and triamines having from about 2 to about 15 carbon atoms where the aromatic groups may be benzene, toluene, naphthalene, anthracene, and the like. It is generally preferred for the aromatic diamines and triamines that the aromatic group be substituted in the ortho, meta and para positions. Typical substituents include lower alkyl amino groups such as ethylamino, propylamino and butylamino, with propylamino being preferred. In the present invention, the dehydrofluorinating agent is preferably an amine compound, such as an amino silane. In a specifically preferred embodiment of the invention, the amino silane is of the general formula NH₂ (CH₂)_(n) NH(CH₂)_(m) Si (OR)_(t) (R')_(w) !, wherein n and m are numbers from about 1to about 20, preferably from about 2 to about 6; t+w=3; R and R'are an aliphatic chain having from about 1 to about 20 carbon atoms (for example, methyl, ethyl, propyl, butyl, and the like), or an aromatic group of from about 4 to about 18 carbons, such as for example in embodiments, benzene, tolyl, xylyl, etc. Examples include 4-aminobutyldimethyl methoxysilane, 4-aminobutyl triethoxysilane, (aminoethylaminomethyl)phenyl triethoxysilane, (aminoethyl aminomethyl) phenyl trimethoxy silane, 3-(N-styrylemethyl-2-aminoethylaminopropy)trimethoxy silane, N-(2-aminoethyl)-3-aminopropylmethyl dimethoxysilane, -N-(2-aminoethyl-3-aminopropyl)trimethoxy silane, N-(2-aminoethyl)-3-aminopropyl tris(2-ethyl-hexoxy)silane, N-(6-aminohexyl)aminopropyltrimethoxysilane, 3-(1-aminopropoxy)-3,3-dimethyl-1-propenyl-trimethoxysilane, 3-aminopropyl tris(methoxyethoxyethoxy)-silane, 3-aminopropyldimethyl ethoxysilane, 3-aminopropylmethyl diethoxysilane, 3-aminopropyl diisopropylethoxysilane, 3-aminopropyl triethoxysilane, 3-aminopropyl trimethoxysilane, 3-aminopropyltris (trimethylsiloxy)silane. Preferred amino silanes include 3-(N-styrylmethyl-2-aminoethyl aminopropyl) trimethoxy silane (S-1590, available from Huls of America, Inc. Piscataway, N.J. in its hydrochloride form), N-(2-aminoethyl-3aminopropyl)-trimethoxy silane (AO700, available from Huls of America), and (aminoethyl aminomethyl) phenyl trimethoxy silane (also available from Huls of America).

The amino silane as the dehydrofluorinating agent is present in the reaction mixture in an amount of from about 0.5 to about 10 percent based on the weight of fluoroelastomer. It is preferable that the amino silane be present in an amount of from about 1 to about 5 weight percent. Specifically preferred amounts are from about 1 to about 2 weight percent.

Although the mechanism of reaction by use of the amino silane is not exactly known, the amino compounds act as both a crosslinker and a coupler. Therefore, there is no need for additional couplers and crosslinkers to be added during the curing process. Specifically, the amino silane is an aminoalkyl functional silane, and has an amine functionality at one end and trialkoxysilane at the other. The dual functionality of the amino silane suggests that the amine is chemically bonded to fluoropolymer, allowing the trialkyl silane functionality to bring about a condensation reaction between fluoropolymer molecules under certain conditions. In contrast, the most probable mechanism for VC-50 and other known curatives is that the crosslinking of fluoropolymer chains occurs through a single reactive functionality.

After the amino silane is added to the fluoroelastomer, the mixture is stirred at room temperature (about 25° C.) to ensure complete mixing. The mixture is stirred by hand or with a mechanical stirrer for a time of from about 1 to about 10 minutes, preferably approximately 5 minutes.

Other adjuvants and fillers may be incorporated in the elastomer in accordance with the present invention as long as they do not affect the integrity of the fluoroelastomer. Such fillers normally encountered in the compounding of elastomers include coloring agents, reinforcing fillers, and processing aids. Oxides such as copper oxides may be added in amounts such as, for example, from about 0.5 to about 30 percent by weight, preferably from about 5 to about 15 percent by weight of total solids, to fuser roll coatings to provide sufficient anchoring sites for functional release oils, and thereby allow excellent toner release characteristics from such members. These adjuvants and fillers can be added along with the addition of the curing agent, for example, an amino silane.

The substrate for the fusing member, including donor fuser rolls and pressure fuser rolls, according to the present invention may be of any suitable material. Typically, it takes the form of a cylindrical tube of aluminum, copper, steel or certain plastic materials chosen to maintain rigidity, structural integrity, as well as being capable of having the silicone elastomer coated thereon and adhered firmly thereto. It is preferred that the supporting substrate is a cylindrical sleeve having an outer layer of from about 1 to about 6 mm. In one embodiment, the core which may be a steel cylinder is degreased with a solvent and cleaned with an abrasive cleaner prior to being primed with a primer, such as Dow Corning 1200, which may be sprayed, brushed or dipped, followed by air drying under ambient conditions for thirty minutes and then baked at 1500° C. for 30 minutes.

Optional intermediate adhesive layers and/or elastomer layers may be applied to achieve desired properties and performance objectives of the present invention. An adhesive layer may be selected from, for example, epoxy resins and aminosilanes. Preferred adhesives are proprietary materials such as THXON 403/404, Union Carbide A-1100, Dow TACTIX 740, Dow TACTIX 741, and Dow TACTIX 742. A preferred curative for the aforementioned adhesives is Dow H41.

A silicone elastomer intermediate layer may be applied according to conventional techniques such as injection molding and casting after which it is cured for up to 15 minutes and at 120° to 180° C. to provide a complete cure without a significant post cure operation. This curing operation should be substantially complete to prevent debonding of the silicone elastomer from the core when it is removed from the mold. Thereafter, the surface of the silicone elastomer is sanded to remove the mold release agent and it is wiped clean with a solvent such as isopropyl alcohol to remove all debris. The intermediate layer can also be prepared from fluoroelastomers like VITON GF®, wherein a typical composition is prepared, for example, by adding 30 PARTS per 100 parts of VITON GF™, carbon black like REGAL N991^(R), followed by rubber milling in a Banbury Mixer and thereafter, injection molded onto a metal core. Alternatively, the intermediate layer may be formed in accordance with the present invention. The thickness of the intermediate layer is from about 0.5 to about 20 mm, preferably from about 1 to about 5 mm.

The resulting fluoroelastomer solution is then used to fabricate the outer layer of a fuser member by conventional solution coating methods spraying, dipping, flow coating, or the like. The coating thickness can vary depending upon specific applications from about 25 to about 75 micrometers thick. The coating is first air dried and then step heat cured in air. For fuser application, the thickness of the dry fluoroelastomer layer could be any suitable thickness, preferably between about 35 to about 50 micrometers.

This thickness range is selected to provide a layer thin enough to prevent a large thermal barrier for fusing and thick enough to allow a reasonable wear life. While molding, extruding and wrapping techniques are alternative means which may be used, it is preferred to spray successive applications of the solvent solution. When the desired thickness of coating is obtained, the coating is cured and thereby bonded to the roll surface. When the desired thickness of coating is obtained, the coating is cured and thereby bonded to the roll surface.

The curing time is from about 30 minutes to about 24 hours, and preferred is from about 4 to about 10 hours. The temperature for curing is from about 100 to about 250° C,, preferably from about 150 to about 230° C.

The present invention greatly reduces the cost and time associated with providing a fluoroelastomer surface on a supporting substrate. Specifically, the present invention dispenses with the additional costs associated with materials which were previously necessary to effect curing, such as the coupling and crosslinking agents, along with basic metal oxides. In addition, a significant cost associated with the curing process is the roll milling step or the final ball milling step. By dispensing with the need for the roll milling and final ball milling steps, the present inventions saves time as well as expense. The unit manufacturing costs can be reduced substantially with embodiments of the present invention.

In addition to cost reduction and time savings, with embodiments of the present invention there is provided a fluoroelastomer surface with sufficient chemical, physical and thermal stability, as well as increased toughness.

The following examples further define and describe fuser members prepared by the present invention and illustrate embodiments of the present invention. Unless otherwise indicated, all parts and percentages are by weight

All the patents and applications referred to herein are hereby specifically, and totally incorporated herein by reference in their entirety in the instant specification.

EXAMPLES

The Viton used in the following examples was obtained from DuPont and is sold under trade name Viton GF®. The amino silane to said dissolved fluoroelastomer. (N-(2-aminoethyl-3-aminopropyl)trimethoxy silane) was obtained from Huls of America Inc., Piscataway, N.J.

Preparation of fluoroelastomer stock solution

A solution of fluoroelastomer stock solution was prepared by dissolving 2,500 grams of Viton GF® in 25 liters of a 3:1 mixture of methylethyl ketone (MEK) and methylisobutylketone (MIBK), by stirring at room temperature (25° C.). This is accomplished by vigorous stirring using a mechanical stirrer. It takes approximately two to four hours to accomplish the dissolution depending upon the intensity of stirring. The resulting solution was then used as stock solution to prepare cured films with different levels of amino silane (AO0700).

Example 1

Curing of Viton GF using 1% by weight A0700

To 250 grams of the above solution, 2.5 grams of amino silane (AO700) was added. The solution was stirred to ensure complete mixing (approximately 5 minutes). The resulting solution was then spray coated onto an aluminum substrate. The resulting film was then air dried overnight. The film was then removed from the aluminum substrate and cured by the typical step heat curing process. The typical step curing process is heating for 2 hours at 93° C., followed by 2 hours at 149° C., followed by 2 hours at 177° C. followed, by 2 hours at 208° C., and 16 hours at 232° C. The resulting thickness of the dry cured film was found to be 9.4 mils. The physical properties were determined by using an Instron Tensile Test Machine. The physical properties of this film were as follows: toughness 2228 in-lb/in³ ; initial modulus 525 psi; elongation; 679%; tensile strength 876 psi.

Example 2

Curing of Viton GF using 2% by weight A0700

Another film was prepared using the method described in Example 1 with the exception that 5 grams of AO0700 was added instead of 2.5 grams. The thickness of the final dry film was determined to be 10.8 mils. The physical properties of this film were as follows: toughness 2601 in-lb/in3; initial modulus 764 psi; elongation; 630%; tensile strength 1220 psi.

Example 3

Curing of Viton GF using 3% by weight A0700

Another film was prepared using the method described in Example 1 with the exception that 7.5 grams of AO700 was added instead of 2.5 grams. The thickness of the final dry film was determined to be 8.8 mils. The physical properties of this film were as follows: toughness 1622 in-lb/in3; initial modulus 759 psi; elongation; 413%; tensile strength 917 psi.

Example 4

Curing of Viton GF using 4%by weight A0700

Another film was prepared using the method described in Example 1 with the exception that 10 grams of AO700 was added instead of 2.5 grams. The thickness of the final dry film was determined to be9.6 mils. The physical properties of this film were as follows: toughness 1398 in-lb/in3; initial modulus 679 psi; elongation; 363%; tensile strength 896 psi.

Example 5

Curing of Viton GF using 5% by weight A0700

Another film was prepared using the method described in Example 1 with the exception that 12.5 grams of A0700 was added instead of 2.5 grams. The thickness of the final dry film was determined to be 8.7 mils. The physical properties of this film were as follows: toughness 749 in-lb/in3; initial modulus 780 psi; elongation; 200%; tensile strength 780 psi.

The details of the mechanical properties of the films cured with 1 to 5% by weight of A0700 to the weight of Viton GF® in solution are summarized in Table 1 set forth below.

                                      TABLE 1                                      __________________________________________________________________________     Curing studies with AO700 added from 1% to 5% to Viton GF ® solution       (no oxides and no ball milling)                                                            Toughness                                                                            Initial Modulus                                                                        Film Thickness                                                                         Elongation                                                                           Tensile Strength                       Sample Description                                                                         (in-lb/in.sup.3)                                                                     (psi)   (mil)   (%)   (psi)                                  __________________________________________________________________________     Viton GF + 1% AO700                                                                        2228  525     9.4     679   876                                    Viton GH + 2% AO700                                                                        2601  764     10.8    630   1220                                   Viton GF + 3% AO700                                                                        1622  759     8.8     413   917                                    Viton GF + 4% AO700                                                                        1398  679     9.6     363   896                                    Viton GF + 5% AO700                                                                        749   780     8.7     200   780                                    __________________________________________________________________________

Example 6

Heat aging study of Viton GF cured with 1% A0700

The film from Example 1 was heat aged for 24 weeks by maintaining the oven temperature at 400° F. The specimens were periodically taken for mechanical property testing as listed in Table 2 below. It should be noted that after 24 weeks of heat aging, the mechanical properties did not degrade. The toughness changed from 2228 to 2286 in-lb/in³, the percent elongation changed from 679 to 736, and tensile strength changed from 876 to 823 psi. These changes are within measurement and acceptable limits.

                                      TABLE 2                                      __________________________________________________________________________     Heat Aging Studies of Viton GF Cured with AO700                                            Toughness                                                                            Initial Modulus                                                                        Film Thickness                                                                         Elongation                                                                           Tensile Strength                       Sample Description                                                                         in-lb/in.sup.3                                                                       (psi)   (mil)   (%)   (psi)                                  __________________________________________________________________________     Viton GF + 1% AO700                                                                        2228  525     9.4     679   876                                    Viton GF + 1% AO700                                                                        3731  424     9.6     758   1489                                   (8 weeks at 400° F.)                                                    Viton GF + 1% AO700                                                                        2952  --      10.0    735   1172                                   (16 weeks @ 400° F.)                                                    Viton GF + 1% AO700                                                                        2286  --      9.7     736   823                                    (24 weeks at 400° F.)                                                   __________________________________________________________________________

Example 7

Heat aging study of Viton GF film cured with 2% A0700

The film from Example 2 was heat aged for 24 weeks by maintaining the oven temperature at 400° F. The specimens were periodically taken for mechanical property testing as listed in Table 3 below. It should be noted that after 24 weeks of heat aging the mechanical property did not degrade considerably. The toughness changed from 2601 to 2342 in-lb/in³, percent elongation changed from 630 to 674, and tensile strength changed from 1220 to 934 psi. These changes are within measurement and accessible limits.

                                      TABLE 3                                      __________________________________________________________________________                 Toughness                                                                            Initial Modulus                                                                        Film Thickness                                                                         Elongation                                                                           Tensile Strength                       Sample Description                                                                         (in-lb/in.sup.3)                                                                     (psi)   (mil)   (%)   (psi)                                  __________________________________________________________________________     Viton GF + 2% AO700                                                                        2601  764     10.8    630   1220                                   Viton GF + 2% AO700                                                                        2862  494     11.5    650   1282                                   (8 weeks at 400° F.)                                                    Viton GF + 2% AO700                                                                        2342  --      10.9    674   934                                    (16 weeks at 400° F.)                                                   __________________________________________________________________________

Example 8

Heat aging study of Viton GF cured with 3% A0700

The film from Example 3 was heat aged for 36 weeks by maintaining the oven temperature at 400° F. The specimens were periodically taken for mechanical property testing as listed in Table 4 set forth below. It should be noted that after 36 weeks of heat aging the mechanical property did not degrade considerably. The toughness changed from 1622 to 1650 in/lbin³, percent elongation changed from 413 to 487, and tensile strength changed from 1917 to 784 psi.

                                      TABLE 4                                      __________________________________________________________________________                 Toughness                                                                            Initial Modulus                                                                        Film Thickness                                                                         Elongation                                                                           Tensile Strength                       Sample Description                                                                         (in-lb/in.sup.3)                                                                     (psi)   (mil)   (%)   (psi)                                  __________________________________________________________________________     Viton GF + 3% AO700                                                                        1622  759     8.8     413   1917                                   Viton GF + 3% AO700                                                                        1505  --      8.7     466   --                                     (8 weeks at 400° F.)                                                    Viton GF + 3% AO700                                                                        1908  555     8.5     510   --                                     (24 weeks at 400° F.)                                                   Viton GF + 3% AO700                                                                        1650  631     8.4     487    784                                   (36 weeks at 400° F.)                                                   __________________________________________________________________________

Example 9

Heat aging study of Viton GF cured with 4% A0700

The film from Example 4 was heat aged for 36 weeks by maintaining the oven temperature at 400° F. The specimens were periodically taken for mechanical property testing as listed in Table 5 below. It should be noted that after 36 weeks of heat aging the mechanical property did not degrade considerably. The toughness changed from 1398 to 1484 in-lbin³, percent elongation changed from 363 to 411, and tensile strength changed from 896 to 826psi.

                                      TABLE 5                                      __________________________________________________________________________                 Toughness                                                                            Initial Modulus                                                                        Film Thickness                                                                         Elongation                                                                           Tensile Strength                       Sample Description                                                                         (in-lb/in.sup.3)                                                                     (psi)   (mil)   (%)   (psi)                                  __________________________________________________________________________     Viton GF + 4% AO700                                                                        1398  679     9.6     363   896                                    Viton GF + 4% AO700                                                                        1685  --      9.3     422   715                                    (8 weeks at 400° F.)                                                    Viton GF + 4% AO700                                                                        1621  479     9.3     417   903                                    (24 weeks at 400° F.)                                                   Viton GF + 4% AO700                                                                        1484  424     9       411   826                                    (36 weeks at 400° F.)                                                   __________________________________________________________________________

Example 10

Heat aging study of Viton GF cured with 5% A0700

The film from Example 5 was heat aged for 36 weeks by maintaining the oven temperature at 400° F. The specimens were periodically taken for mechanical property testing as listed below in Table 6. It should be noted that after 36 weeks of heat aging the mechanical property did not degrade considerably. The toughness changed from 749 to 769 in-lbin³, percent elongation changed from 200 to 246, and tensile strength changed from 780 to 639 psi.

                                      TABLE 6                                      __________________________________________________________________________                 Toughness                                                                            Initial Modulus                                                                        Film Thickness                                                                         Elongation                                                                           Tensile Strength                       Sample Description                                                                         (in-lb/in.sup.3)                                                                     (psi)   (mil)   (%)   (psi)                                  __________________________________________________________________________     Viton GF + 5% AO700                                                                        749   780     8.7     200   780                                    Viton GF + 5% AO700                                                                        934   --      8.7     --    --                                     (8 weeks at 400° F.)                                                    Viton GF + 5% AO700                                                                        975   585     8.5     --    --                                     (24 weeks at 400° F.)                                                   Viton GF + 5% AO700                                                                        769   539     8.3     --    639                                    (36 weeks at 400° F.)                                                   __________________________________________________________________________

Example 11

Curing of Viton GF® with 2% A0700 in the presence of copper oxide

To 250 grams of the stock solution, 4 grams of copper oxide and 5 grams of amino silane (A0700) was added. These contents were then stirred vigorously with a mechanical stirrer for 10 minutes after which time the resulting dispersion was then spray coated on to aluminum substrate. The resulting film was then air dried overnight. The film was removed from the aluminum substrate and cured by the typical step heat curing process described in the above examples. The resulting thickness of the dry cured film was found to be 10.3 mils. The mechanical properties of this film as determined by the Instron were as follows: toughness 4856 in-lb/in³ ; initial modulus 743 psi; elongation 719%; and tensile strength 2017 psi. This film was then heat aged by maintaining the oven temperature of 400° F in air show for 16 weeks. No degradation of the physical properties was observed. The toughness of the heat aged sample was 4549 in-lb/in³ ; elongation 1058%; tensile strength 1028 psi. Table 7 below shows the details of the mechanical properties.

                                      TABLE 7                                      __________________________________________________________________________                      Toughness                                                                            Initial Modulus                                                                        Film Thickness                                                                         Elongation                                                                           Tensile Strength                  Sample Description                                                                              (in-lb/in.sup.3)                                                                     (psi)   (mil)   (%)   (psi)                             __________________________________________________________________________     Viton GF + 2% AO700 + 15% CuO                                                                   4856  743     10.3    719   2017                              (control)                                                                      Viton GF + 2% AO700 + 15% CuO                                                                   3434  995     10.5    737   1322                              8 weeks at 400° F.)                                                     Viton GF + 2% AO700 + 15% CuO                                                                   4549  not enough                                                                             10.3    1058  1028                              (16 weeks at 400° F.)                                                                          sample                                                  __________________________________________________________________________

The mechanical property data indicate that the samples prepared from A0700 as the curing agent maintain physical properties. These samples were aged at 400° F. for up to 24 weeks. The mechanical properties were tested at regular intervals and no significant change was observed. The data indicate that A0700 used as a curative presents an elastomer surface having increased toughness and tensile strength. In addition, along with the superior properties of the resulting elastomer, the cost of the process for providing an elastomer surface is decreased due to the fact that additional crosslinkers and couplers in addition the roll milling and ball milling steps are not needed.

While the invention has been described in detail with reference to specific and preferred embodiments, it will be appreciated that various modifications and variations will be apparent to the artisan. All such modifications and embodiments as may readily occur to one skilled in the art are intended to be within the scope of the appended claims. 

We claim:
 1. A ball milling-free and roll milling-free method for providing a fluoroelastomer on a supporting substrate comprising:a) dissolving a fluoroelastomer; b) adding and reacting an amino silane in an amount of from about 0.5 to about 10 weight percent based on the weight of said fluoroelastomer to said dissolved fluoroelastomer to form a resulting homogeneous fluoroelastomer solution; and c) subsequently providing at least one layer of the homogeneous fluoroelastomer solution to said supporting substrate.
 2. A method in accordance with claim 1, wherein the amino silane is of the formula NH₂ (CH₂)_(n) NH(CH₂)_(m) Si (OR)_(t) (R')_(w) !, wherein n and m are a number of from about 1 to about 20; t+w=3; and R and R' are an aliphatic hydrocarbon chain having from about 1 to about 20 carbon atoms or an aromatic group having from about 4 to about 18 carbons.
 3. A method in accordance with claim 2, wherein the amino silane is selected from the group consisting of N-(2-aminoethyl-3-aminopropyl)-trimethoxy silane, 3-(N-styrylmethyl-2-aminoethyl aminopropyl) trimethoxy silane, (aminoethyl aminomethyl) phenyl trimethoxy silane, and (aminoethyl aminomethyl) phenyl triethoxy silane.
 4. A method in accordance with claim 1, wherein the amount of amino silane is from about 1 to about 5 weight percent.
 5. A method in accordance with claim 4, wherein the amount of amino silane is from about 1 to about 2 weight percent.
 6. A method in accordance with claim 1, wherein the fluoroelastomer is selected from the group consisting of (1) a class of copolymers of vinylidenefluoride and hexafluoropropylene, (2) a class of terpolymers of vinylidenefluoride, hexafluoropropylene and tetrafluoroethylene, and (3) a class of tetrapolymers of vinylidenefluoride, hexafluoropropylene. tetrafluoroethylene, and a cure site monomer.
 7. A method in accordance with claim 1, wherein the fluoroelastomer is selected from the group consisting of poly (vinylidene fluoride-hexafluoropropylene) and poly (vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene).
 8. A method in accordance with claim 1, wherein the fluoroelastomer comprises 35 weight percent of vinylidenefluoride, 34 weight percent of hexafluoropropylene and 29 weight percent of tetrafluoroethylene.
 9. A method in accordance with claim 1, wherein the fluoroelastomer is added in an amount of from about 1 to about 75 percent by weight of total solids.
 10. A method in accordance with claim 9, wherein the fluoroelastomer is added in an amount of from about 5 to about 30 percent by weight of total solids.
 11. A method in accordance with claim 1, wherein the fluoroelastomer is dissolved in a solvent selected from the group consisting of methyl ethyl ketone and methyl isobutyl ketone.
 12. A method in accordance with claim 1, wherein said homogeneous fluoroelastomer solution provided on said supporting substrate is heat cured.
 13. A method in accordance with claim 12, wherein said heat curing occurs at a temperature of from about 100 to about 250° C. for a time of from about 30 minutes to about 24 hours.
 14. A method in accordance with claim 13, wherein the temperature is from about 150° to about 250° C. and the time is from about 4 to about 10 hours.
 15. A method for providing a fluoroelastomer surface on a supporting substrate comprising:a) dissolving a fluoroelastomer; b) adding and reacting N-(2-aminoethyl-3aminopropyl)-trimethoxy silane to said dissolved fluoroelastomer to form a resulting homogeneous fluoroelastomer solution; c) subsequently providing at least one layer of the homogeneous fluoroelastomer solution to said supporting substrate.
 16. A method in accordance with claim 1, further comprising adding in addition to amino silane, copper oxide in an amount of from 0.5 to about 30 percent by weight of total solids.
 17. A method in accordance with claim 16, wherein copper oxide is added in an amount of from about 5 to about 15 percent by weight of total solids.
 18. A method in accordance with claim 8, wherein said fluoroelastomer further comprises 2 weight percent of a cure site monomer.
 19. A ball milling-free and roll milling-free method for providing a fluoroelastomer surface on a supporting substrate comprising:a) dissolving a fluoroelastomer; b) adding and reacting an amino silane having the formula NH₂ (CH₂)_(n) NH (CH₂)_(m) Si (OR)_(t) (R')_(w) !, wherein n and m are a number of from about 1 to about 20; t+w=3; and R and R' are an aliphatic hydrocarbon chain having from about 1 to about 20 carbon atoms or an aromatic group having from about 4 to about 18 carbons in an amount of from about 0.5 to about 10 weight percent based on the weight of said fluoroelastomer, to said dissolved fluoroelastomer to form a resulting homogeneous fluoroelastomer solution; c) subsequently providing at least one layer of the homogeneous fluoroelastomer solution to said supporting substrate. 